A flexible instrument comprises a first link and a second link that each comprise a first end, a second end, and a wall extending between the first end and the second end, the wall comprising an outer wall surface and an inner wall surface; an outer ear extending in a first axial direction away from the first end of the link; an inner bearing surface defined at the first end of the link, the inner bearing surface extending between the outer ear and the inner wall surface; an inner ear extending in a second axial direction away from the second end of the link; and an outer bearing surface defined at the second end of the wall, the inner bearing surface extending between the inner ear and the outer wall surface. The instrument further comprises at least one of a position sensor and an orientation sensor located along the wall of the instrument.